In general, a large number of fibers, such as, acrylic fibers, vinyl chloride based fibers, and polyamide fibers, or polyester fibers are marketed as artificial fibers for hair. However, since these fibers are not simultaneously provided with all characteristics necessary as an artificial fiber for hair, such as heat resistance, curling property, and touch, each material has limited advantageous style fields for wigs. For example, conventional fibers are classified into synthetic fibers suitable for curly style, or synthetic fibers suitable for straight style, respectively, and since only a few synthetic fibers having wide stylability (fiber function enabling various styles for wigs) are marketed, development of such synthetic fibers are now demanded. For this reason, in order to improve stylability, for example, Japanese Patent Laid-Open No. 55-158322 official report, Japanese Patent Laid-Open No. 56-63006 official report, and Japanese Patent Laid-Open No. 58-4809 official report disclose techniques for accomplishing objects thereof by giving specific unevenness to a fiber surface. Although application of specific unevenness to a fiber surface is effective method for improvement in stylability, indeed, only application of simple surface unevenness cannot improve rigidity of the fiber, and, as a result, cannot sufficiently satisfy salability of straight style. Low heat resistance thereof does not allow use of thermal instruments, such as hair driers, and does not easily enable creation of hair style suitable for taste of each individual, and therefore many users require improvement in the point.